Sound reproducing apparatus



May 9, 1939. G. w. BLESSING. ET AL SOUND REPRODUCING APPARATUS FiiedNov.

5, 1937 2 Sheets-Sheet l I/Vl/Ii'N'l'ORS Gregory VI Blessing Emile C'-Guedon Littomeg May 9, 1939. G. w. BLESSING ET AL 2,157,158

SOUND REPRODUCING APPARATUS Filed Nov. 5, 1-937 2 Sheets-Sheet 2INVENTORS Gregory W Blessing Emile C. Guedon (Ittorneg Patented May 9,1939 UNITED STATES PATENT OFFICE Guedon, Audubon, N. 1., asslgnors toRadio Corporation of America, a corporation of Delaware ApplicationNovember 5, 1937, Serial No. 112,886

This invention relates to sound reproducing apparatus, and moreparticularly toa turntable mounting upon a motor, the present inventionbeing an improvement upon that disclosed in the copending application ofH. E. Roys, Serial No.

8,664, filed February 28, 1935, now Patent No. I

2,113,384, granted April 5, 1938, and assigned to Radio Corporation ofAmerica.

In the aforesaid application, there is disclosed a synchronous motor tothe rotor element of which is, connected a record supporting turntableby means of a plurality of circumferentially spaced rigid pins, bolts,or the like. Whilea motor of this type is satisfactory for manypurposes, it has been found that occasionally mechanical vibrations ofthe motor are transferred to the turntable and the record supportedthereby through the aforesaid rigid connection, and this results in whatis known as rumble.

The primary object of our present invention is to provide an improvedmotor and turntable mounting of the type set forth above which will befree from the aforementioned diflicult.

More specifically, it is an object of our present invention to providean improved motor and turntable mounting by means of which mechanicalvibrations arising in the motor will not be transferred through theturntable to the record being reproduced.

Another object of our present invention is to provide an improvedphonograph turntable unit as aforesaid which will rotate a disc recordwithout imparting undesirable slight mechanical vibrations thereto.

Still another object of our present invention is to provide an improvedrecord supporting turntable construction for phonographs wherein thepossibility of transferring mechanical vibrations to the record has beeneliminated from all elements with which the record is in contact.

A further object of our present invention is to provide an improvedsynchronous motor and turn table assembly of the type set forth which isinexpensive of manufacture, which readily lends itself to rapid quantityproduction and which is highly eflicient in use.

In accordance with our present invention, we couple the turntable to therotor of the synchonous motor by means of a plurality of resilientcoupling devices which are capable of absorbing any slight mechanicalvibrations originating in the motor without transferring them to theturntable. To further reduce the possibility of transferring any slightmechanical vibrations which are set up in the motor to the recordsupported on the turntable, we place a rubber bushing around the recordcentering spindle associated with the turntable, and also place a rubbersleeve over the end of the spindle on which the record is threadedlyreceived to be supported on the turntable. An arrangement of this sorteffectively eliminates the possibility of having any slight mechanicalvibrations transferred from the motor to the record, and thus the wellknown rumble is effectively eliminated.

The novel features that we consider characteristic of our invention areset forth with particularity in the appended claims. The inventionitself, both as to its organization and method of operation, togetherwith additional objects and advantages thereof, will best be understoodfrom the following description of several embodiments thereof, when readin connection with the accompanying drawings, in which Figure 1 is aplan view of amotor and turntable assembly formed according to ourinvention,

Figure 2 is a partly elevational and partly sectional view taken on theline II'II of Fig. 1,

Figure 3 is 'a fragmentary view showing the details of the recordcentering spindle associated with the turntable,

Figure 4 is a sectional view of one of the resilient coupling elementswhich couple the turntable to therotor,

Figure 5 is a sectional view showing a modification of our invention,and

Figure 6 is a sectional view showing, in detail, the relation betweenthe record centering spindle ,and the turntable.

Referring. more particularly to the drawings,

wherein similar reference characters designate corresponding partsthroughout, we have shown, in Figs. 1 and 2, a motor comprising asupporting frame I provided with a bushing 3 in which is rotatablyreceived a shaft 5 supported on a thrust bearing 1 in the bushing 3.Fixed to the upper end of the bushing 3 in a manner more fully set forthin the above identified patent is the stator 9 comprising part of aprime mover, such as synchronous motor, the stator being provided with aplurality of peripheral teeth I I constituting pole faces, and having apair of energizing coils 13 mounted thereon. An annular rotor I5 whichconstitutes the rotor element of the prime mover is provided with aseries of internal teeth ll of substantially the same arcuate length asthe teeth H and cooperates with the teeth H to constitute cooperatingpole faces, the rotor l5 bein mounted on a spider 19, as by means of thescrews 2|, and the spider 19 being fixed to like in conventional manner.

the upper end of the shaft in any suitable manner.

The spider I9 is formed with a plurality of cup-shaped retaining members23 in which are received the lower ends of a number of spoolshaped, softrubber coupling members 25, shown in detail in Fig. 4. The upper ends ofthe cou pling members 25 are received in inverted ouplike elements 2'!which are staked or otherwise suitably secured to the lower surface of arecord supporting turntable 29, the upper surface of which may besuitably covered with felt or the The turntable 29 has a central opening3| through which extends a record centering spindle 33threadedlyreceived in the upper end of the shaft 5, as clearly shown in Fig. 3.The spindle 33 is preferably formed with a flange 35 below which arubber bushing 3'! is fitted on the spindle in order tovibration-insulate the spindle 33 from the turntable 29. This preventstransfer of mechanical vibrations from the shaft 5 to the turntable 29through the spindle 33. Above the flange 35, the spindle 33 is providedwith a rubber sleeve 39 which is adapted to threadedly receive a recordR to be supported on the turntable 29 for playing.

It will be seen, from the foregoing description, that we have provided anovel arrangement of motor and turntable in which mechanical vibrationsarising in the motor will be effectively prevented from reaching therecord. The resilient coupling members 25 prevent transfer of thesevibrations directly to the turntable itself. Similarly, the rubbersleeve 31 prevents transfer of mechanical vibrations from the shaft 5 tothe turntable, while the rubber sleeve 39 prevents any vibrations frombeing transmitted from the spindle 33 to the record. In aconstruction'of this sort, therefore, the rumble" usually found inconventional phonographs will be entirely absent.

In Fig. 5, we have shown a modified form of our invention wherein thespider l9 may be formed of a punched disc provided with a series ofcircumferentially spaced openings 4| in which are received the resilientcoupling members 43 corresponding to the coupling members 25 shown inFigs. 1, 2 and 4. The coupling members 43 are also made of soft rubberand are secured to the spider IS in the openings 4|. A plurality of pins45 secured to the turntable 29 are received within the bores of thecoupling members 43 and serve to couple the turntable 29 to the rotor [5through the spider IS in a manner similar to that in Fig. 2.

Although we have shown and described two modifications of our invention,it will; no doubt, be readily apparent to those skilled in the art thatmany other modifications are possible. We desire, therefore, that ourinvention shall not be limited except insofar as is made necessary bythe prior art and by the spirit of the appended claims.

We claim as our invention:

1. In a phonograph, the combination of a prime mover, a recordsupporting turntable, resilient means connecting said turntable withsaid prime mover, a record centering spindle for said turntable,vibration insulating means between said turntable and said spindle, andvibration insulating means surrounding said spindle, said last namedmeans being adapted to threadedly receive a record to be supported onsaid turntable.

2. In a phonograph turntable, the combination of a motor having a rotorelement, a record supporting turntable, a plurality of cooperativeretaining devices on said rotor element and said turntable, andresilient coupling elements carried by said retaining devicesresiliently connecting said turntable to said rotor.

BQThe invention set forth in claim 2 characterized by the addition of arecord centering spindle for said turntable, and vibration insulatingmeans interposed between said spindle and said turntable.

4. The invention set forth in claim 2 characterized by the addition of arecord centering spindle for said turntable, vibration insulating meansinterposed between said spindle and said turntable, and vibrationinsulating means surrounding said spindle, said last named means beingadapted tothreadedly receive a record to be supported on said turntable.

5. The invention set forth in claim 2 characterized in that saidretaining devices are constituted by cup shaped elements, andcharacterized further in that said resilient coupling elements areconstituted by rubber members having their ends seated in said cupshaped elements.

6. In a phonograph, the combination of a synchronous motor comprising aframe, a bushing formed on said frame, a stator carried by said frame, ashaft rotatably carried in said bushing, a spider fixed-to said shaftfor rotation therewith, a rotor associated with said stator andsupported by said spider in cooperative relation to said stator, arecord supporting turntable, and a plurality of resilient couplingelements connecting said turntable to said spider.

'7. In a phonograph, the combination of a synchronous motor comprising aframe, a bushing formed on said frame, a stator carried by said frame, ashaft rotatably carried in said bushing, a spider fixed to said shaftfor rotation therewith, a rotor associated with said stator andsupported by said spider in cooperative relation to said stator, arecord supporting turntable, a plurality of resilient coupling elementsconnecting said turntable to said spider, a record centering spindlesecured to said shaft and extending.

through said turntable, and a rubber bushing interposed between saidspindle and said turntable for preventing transfer of mechanicalvibrations between said turntable and said spindle.

8. In a phonograph, the combinationof a prime mover, a record-supportingturntable, means including a resilient member coupling said turntablewith said prime mover, a record-centering spindle for said turntable,vibration-insulating means between said turntable and said spindle, andvibration-insulating means surrounding said spindle, said last-namedmeans being adapted to threadedly receive a record to be supported onsaid turntable.

9. In a phonograph, the combination of a prime mover including a rotorelement, a record-supporting turntable, means including a resilientmember coupling said turntable with said rotor element, arecord-centering spindle for said turntable, vibration-insulating meansbetween said turntable and said spindle, and vibration-insulating meanssurrounding said spindle, said lastnamed means being adapted tothreadedly receive a record to be supported on said turntable.

- GREGORY W. BLESSING.

EMILE C. GUEDON.

